Get rid of crc32, truncate instead

Signed-off-by: Matt Strapp <matt@mattstrapp.net>

5 files changed, 52 insertions, 11 deletions

diff --git a/app/src/lib/svelte/Navigation.svelte b/app/src/lib/svelte/Navigation.svelte
index 20c7d8b..fd3c914 100644
--- a/app/src/lib/svelte/Navigation.svelte
+++ b/app/src/lib/svelte/Navigation.svelte
@@ -7,5 +7,5 @@
   <svelte:fragment slot="lead">
     <AppRailAnchor href="/" selected={$page.url.pathname === '/'}>Home!</AppRailAnchor>
   </svelte:fragment>
-	<AppRailAnchor href="/crc32" selected={$page.url.pathname === '/crc32'}>CRC32</AppRailAnchor>
+	<AppRailAnchor href="/truncate" selected={$page.url.pathname === '/truncate'}>Truncate!</AppRailAnchor>
 </AppRail>
diff --git a/app/src/lib/ts/crc32.worker.ts b/app/src/lib/ts/crc32.worker.ts
deleted file mode 100644
index 57c1bc9..0000000
--- a/app/src/lib/ts/crc32.worker.ts
+++ /dev/null
@@ -1,10 +0,0 @@
-// TODO: Think about using a WebAssembly implementation of CRC32 instead of JavaScript.
-// WHY? The JavaScript implementation is not very extensible and is not very fast.
-import crc32 from 'crc/crc32';
-
-onmessage = async (message: MessageEvent<File>) => {
-  const file = message.data;
-  const buffer = await file.arrayBuffer();
-  const crc = crc32(buffer);
-  postMessage(crc);
-};
diff --git a/app/src/lib/ts/download.ts b/app/src/lib/ts/download.ts
new file mode 100644
index 0000000..a6167d7
--- /dev/null
+++ b/app/src/lib/ts/download.ts
@@ -0,0 +1,33 @@
+// Yoinked from https://web.dev/patterns/files/save-a-file/ for the polyfill
+
+export default async function saveFile(blob: ArrayBuffer, suggestedName: string | undefined) {
+	const supportsFSAccess = 'showSaveFilePicker' in window &&
+		(() => {
+			try {
+				return window.self === window.top;
+			} catch {
+				return false;
+			}
+		})();
+
+	if (supportsFSAccess) {
+		try {
+			const handle = await window.showSaveFilePicker({
+				suggestedName: suggestedName,
+			})
+			const writable = await handle.createWritable();
+			await writable.write(blob);
+			await writable.close();
+		} catch (err: unknown) {
+			// TypeScript
+			if ((err as Error)?.name !== 'AbortError') {
+				console.error(err);
+			}
+		}
+	} else {
+		const anchor = document.createElement('a');
+		anchor.download = suggestedName ?? 'truncated';
+		anchor.href = URL.createObjectURL(new Blob([blob]));
+		anchor.click();
+	}
+}
\ No newline at end of file
diff --git a/app/src/lib/ts/truncate.worker.ts b/app/src/lib/ts/truncate.worker.ts
new file mode 100644
index 0000000..52eebb7
--- /dev/null
+++ b/app/src/lib/ts/truncate.worker.ts
@@ -0,0 +1,10 @@
+import type { TruncateRequest, TruncateResponse } from '../types/truncate-worker';
+
+
+onmessage = async (message: MessageEvent<TruncateRequest>) => {
+	const file = message.data.file;
+	const buffer = await file.arrayBuffer();
+	const truncated = buffer.slice(0, message.data.size);
+
+	postMessage({ file: truncated } as TruncateResponse);
+}
\ No newline at end of file
diff --git a/app/src/lib/types/truncate-worker.ts b/app/src/lib/types/truncate-worker.ts
new file mode 100644
index 0000000..9b1872f
--- /dev/null
+++ b/app/src/lib/types/truncate-worker.ts
@@ -0,0 +1,8 @@
+export type TruncateRequest = {
+	file: File,
+	size: number,
+};
+
+export type TruncateResponse = {
+	file: ArrayBuffer,
+};